It is the time of the year when insects, diseases, and various fungus begin to use our trees for groceries. Each of these problems has a specific host that it prefers and a place it likes to occupy. There are literally hundreds of books on these subjects so I am just going to hit the high spots for what we find here in our nursery.
1). We who have oaks on our property will probably see little green worms hanging from fine silk threads. These are the larva stage of the oak moth. They will crawl around and make a green mess, eat like pigs and then build a small house where they change from a worm into a flying insect (the moth). The moths flutter all over the place, the birds have a feast, and then after the party the moths lay the eggs that will become next year’s worms — and then die. Ah…..the glory of life.
2). Aphids are quite happy to be gathering on the most tender parts of our plants. They don’t bother pines or junipers much but they love roses, crabapples, elms, oaks, and any other plant that is producing a soft green, new growth that is easily penetrated by their sucking mouth parts. Look around for shiny leaves that have sticky stuff on them (this is called honeydew and is aphid poo). Ants love the poo and the ants come with sooty mold fungus on their feet and then you have all kinds of problems. Mix 1 ounce of alcohol and about 8-10 drops of baby shampoo with 16 ounces of water and then spray; it will make them go away. Be nice to lady bugs; they are champion aphid eaters. Also praying mantis are voracious eaters of other insects.
3). Scale insects are very busy right now. They are difficult to detect because they don’t move around and are often given an appearance that makes them look very much like the bark they are stuck to. They live inside a hard shell and don’t respond well to insecticides. We use a toothbrush or small pick and squash them and then gently brush the area with Volck oil. Don’t get oil on any leaves and don’t use Malathion because both of these will burn your trees. Look closely where the branch leaves the trunk; look for a little bump that should not be there. If you can squish it, you have scale. If you see one scale there are always many more. Be vigilant.
4). Various mildews, molds, whorls, and other stuff will turn up from time to time. For these conditions and most fungus, the best offense is a good defense; so spray with dormant oil in December and then again in February. If you do this for a couple of years these kinds of problems will decline dramatically.